Method and apparatus for producing high hydraulic pressure, particularly for operating a forging press

ABSTRACT

A method for producing high hydraulic pressures for rapidly moving press pistons using a pressure transducer, for example, a piston of two distinct diameters moving in associated cylinders, comprises storing gas at high pressure in a storage container and feeding the high pressure gas to the pressure transducer during the operation thereof. The primary or large diameter part of the transducer is connected to a gas chamber under high pressure. The gas chamber is supplied with the gas at high pressure by a separate pump. The transmission ratio of the gas pressure to the liquid pressure in a pressure transducer varies between (1 to 2 and 1 to 5) 1:2 and 1:5. The apparatus includes an arrangement in which there is a second pressure transducer which is connected to the first transducer for effecting the return stroke thereof and which includes a secondary side which is in communication with the secondary side of the first transducer during the forward stroke thereof. During the return stroke, the secondary side of the second transducer is fed, for example, from an air vessel under pressure while the primary side is in communication with a high level pressure storage tank.

United States Patent 1 Muller [76] Inventor: Ernest M'iiller, Konigsberger Str. 18,

Bad Breisig, Germany [22] Filed: Feb. 1, 1971 [21] Appl. No.: 111,182

[30] Foreign Application Priority Data Mar. 19, 1970 Germany ..P 20 13 120.8

[52] US. Cl ..60/51, 60/52 HF, 60/54.5 HA [51] Int. Cl ..F15b 3/00 [58] Field of Search ..60/51, 54.5 HA, 52 HF [56] References Cited UNITED STATES PATENTS 1,966,421 7/1934 Towler ..60/54.5 H 2,032,185 2/1936 Sciaky ..60/54.5 HA 3,145,627 8/1964 Neukom ..60/5l Primary ExaminerEdgar W. Geoghegan Attorney- McGlew & Tuttle METHOD AND APPARATUS FOR PRODUCING HIGH HYDRAULIC PRESSURE, PARTICULARLY FOR OPERATING A FORGING PRESS 1 May 15, 1973.

57 ABSTRACT A method for producing high hydraulic pressures for rapidly moving press pistons using a pressure transducer, for example, a piston of two distinct diameters moving in associated cylinders, comprises storing gas at high pressure in a storage container and feeding the high pressure gas to the pressure transducer during the operation thereof. The primary or large diameter part of the transducer is connected to a gas chamber under high pressure. The gas chamber is supplied with the gas at high pressure by a separate pump. The transmission ratio of the gas pressure to the liquid pressure in a pressure transducer varies between (1 to 2 and 1 to 5) 1:2 and 1:5. The apparatus includes an arrangement in which there is a second pressure transducer which is connected to the first transducer for effecting the return stroke thereof and which includes a secondary side which is in communication with the secondary side of the first transducer during the forward stroke thereof. During the return stroke, the secondary side of the second transducer is fed, for example, from an air vessel under pressure while the primary side is in communication with a high level pressure storage tank.

9 Claims, 1 Drawing Figure METHOD AND APPARATUS FOR PRODUCING HIGH HYDRAULIC PRESSURE, PARTICULARLY FOR OPERATING A FORGING PRESS SUMMARY OF THE INVENTION This invention relates in general to a method and apparatus for the production of high hydraulic pressures and, in particular, to a new and useful system and method for supplying heavy hydraulic forging presses with actuating pressure during their operation.

Heavy hydraulic forging presses are used mainly in aircraft construction for the production of airplane parts of light metals and their alloys. The maximum pressure is only required on a relatively small working stroke. In view of the desirability of a low purchase cost, the presses are equipped only for high operating pressure, which is produced by a pressure transducer whose primary part is admitted with pressure fluid from a high pressure tank for an operating pressure of about 200 300 excess atmospheres. Such presses have a hand control. The secondary part of the pressure transducer is in communication with the working cylinder of the press and produces in the latter the maximum operating pressure of 500 excess atmospheres and more. This is achieved by filling the working cylinder during the idle down stroke of the press with low pressure fluid, for example, from a high pressure storage tank or air vessel. The idle stroke is .followed by a rough pressing strike effected with pressure fluid from the high pressure reservoir.

If an even higher pressure is required, the pressure fluid from the high pressure reservoir can be conducted to the primary part of the pressure transducer and the pressure can be increased to the maximum value. The piston of the pressure transducer covers a long distance, relative to the press stroke, at a relatively low speed.

The known plants are therefore notsuitable if it is necessary to cover long paths of the press piston at maximum pressure and at high speed. This requirement appears, for example, in the processing of titanium or some heavy metals which must be shaped at high speed over a long distance in the swage.

The invention provides a method and a press plant with which this problem can be solved. It is based on the idea of satisfying the sudden high energy requirement in carrying out the pressure stroke at maximum pressure and long distance by admitting the pressure transducer not with high pressure fluid, but with high pressure gas from the high pressure reservoir. The gas can be conducted at high velocity through a relatively narrow pipe cross-section. If high pressure fluid is to be passed to the pressure transducer, a multiple of the pipe cross-section would be required, and this factor becomes more important when there is a high pressure line between the central station, where the high pressure reservoir is installed, and the press, and which is usually much longer than the connection between the press and the pressure transducer installed nearby.

Besides, by accelerating the liquid mass in the entire return pipe to the transducer at the start of the maximum pressure working stroke, and by the deceleration at the end of this stroke, pressure shocks would be produced in the high pressure plant which must be taken into account in dimensioning all high pressure elements involved.

Such pressure shocks do not appear when gas is used for energy according to the idea of the invention. The amount of maximum pressure fluid for the high pressing speed can also be supplied by a special maximum pressure pumping plant, but this would require much higher expenditures than a pressure transducer fed from the high pressure reservoir.

If several presses are provided, there is no reason why the respective pressure transducers cannot be connected to the same gas chamber of the high pressure reservoir. On the other hand, several pressure transducers can be arranged which deliver maximum pressure fluid to one press simultaneously or successively.

The problem of pressing titanium or similar difficultto-deform metals which requires a high speed piston with a long stroke and maximum pressure is thus solved with the invention in a surprisingly simple manner with a minimum of expenditure.

According to another feature of the invention, the return of the piston in the pressure transducer is solved in a fortunate manner by using a second, smaller pressure transducer or back-pressure transducer. This back-pressure transducer is fed again in the primary part from the high pressure reservoir, namely, from a liquid chamber. In its secondary part there is produced, by the transducer piston, a pressure somewhat higher than in the secondary part of the pressure transducer, which latter is connected to this secondary part. Consequently, the piston of the pressure transducer is moved in the direction of the starting position. By a number of strokes of the back-pressure transducer, the piston of the pressure transducer is returned step-by-step into the starting position. The preparation of the next pressing operation leaves enough time for this.

For older presses, it is known to use so-called driving apparatus, whose primary part is admitted with steam or compressed air from the compressed air mains of the plant. This requires transmission ratios of 1:30 and more. But because the operation with steam or air is uneconomical, the industry has switched a long time ago to a strictly hydraulic operation.

According to the invention, a new method is used which works with maximum pressure air from the hydraulic reservoir in order to obtain a peak operation with maximum pressure and a long press stroke, and to be able to forge, in the swage, titanium and similar metals, with a high deformation resistance, and to do it at a high deformation rate.

Accordingly, it is an object of the invention to provide a method for producing high hydraulic pressures for rapidly moving press pistons using pressure transducers comprising storing a gas of high pressure and feeding the high pressure gas to the primary part of the pressure transducer, the primary part of the pressure transducer being advantageously held constantly under the load of the gas supplied from the high pressure container during operation.

A further object of the invention is to provide a system for supplying high pressure to moving parts such as a forging press which includes at least one storage tank for storing gas at high pressure and a transducer having a primary part which is connected to the storage tank during the operation and a secondary part which is connected to the cylinder to be supplied with the gas at high pressure and wherein there is advantageously pro vided a second transducer for the return stroke of the primary transducer which has a secondary side which is in communication, during the forward stroke, with the secondary side of the first pressure transducer and which is fed from an air vessel while the primary side is in communication with the high pressure storage tank.

A further object of the invention is to provide a pressure operating system which is simple in design, rugged in construction, and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference should be had to the accompanying drawing and descriptive matter in which there is illustrated a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING The only FIGURE of the drawing is a schematic view of a pressure system for use with a forging press constructed in accordance with the invention.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing in particular, the invention embodied therein includes a high pressure pump 1, which receives liquid from a high level tank 3, which is fed through a conduit 2 and which may be oil, water or any other working fluid. The pump 1 discharges through line 7 into a high pressure storage tank or reservoir 4, which is provided with a maximum-minimum control of any known kind. The vessels and 6 form the gas chamber of the storage unit and are, like the vessel 4, under high pressure of about 300 excess atmospheres.

The gas chamber formed by the top of the vessel 4 and by the vessels 5 and 6 is in communication through the line 8 with a primary cylinder 10 of a first pressure transducer 11. The first pressure transducer 11 includes a piston having a primary part 13, which is slidable in primary cylinder 10, and a second part 14, which is slidable in a secondary cylinder 12. The secondary cylinder 12 is in communication through lines 15 and 18 and valve 16 with the working cylinder 19 of a forging press. The valve 16 is actuated by a movable ram 17. A working piston 20 of the forging press is slidable in the cylinder 19.

The method of operation of the press is as follows:

During the idle downstroke of piston 20, cylinder 19 is filled with a low pressure fluid from the liquid air vessel 38, which connects thereto through the lines 21 and 18 and a fillup valve 24. After the idle stroke is completed and the fillup valve is closed, pressure fluid is conducted through control valve 23 in lines 7, 26 and 18 from the reservoir 4 into the working cylinder 19. The metal is then rough-pressed.

When the rough-pressing stroke is completed, valve 16 is opened by moving a control member 17 which is connected thereto and the maximum pressure for example, a pressure of 700 to 800 excess atmospheres is conducted from secondary cylinder 12 of pressure transducer 11 into working cylinder 19. The maximum pressure fluid can flow through the short lines 15 and 18 which have a large cross-section for delivery of the pressure fluid in a quantity corresponding to the required high working speed of the press. The pressure gas used for the production of the maximum pressure,

supplied from reservoirs 4, 5 and 6, (for example, with 50m/sec or more) flows fast enough through conduit 8. The working stroke of the press can be carried out at high speed with maximum pressure.

After the pressing operation is completed, control valve 22 is opened by an operating control which is schematically indicated so that cylinder chamber 19 expands into lines 18 and 21 to the liquid air vessel 38. Finally, piston 20 is retracted, with a retraction device of the press (not represented), and the working fluid is expelled, after fillup valve 24 has been opened by control 24a, through lines 18 and 21 into the liquid air vessel 38.

The return of the piston in pressure transducer 11 is effected by the back-pressure transducer 30, which acts like a pump. Its offset piston protrudes with its primary part 33 into primary cylinder 31, and, with its secondary part 34, into secondary cylinder 32. When control valve 28 opens, pressure fluid flows from high pressure reservoirs 4, 5 and 6 into lines 7, 26 and 27 and into the primary cylinder 31 to drive the piston portion 33 forward, which in turn moves portion 34 to force fluid at maximum pressure from secondary cylinder 32 through the open outlet valve 35 over and line 39 into secondary cylinder 12 of pressure transducer 11. Piston portions 13 and 14 of pressure transducer 11 are moved back. After the stroke of piston 33, 34 of backpressure transducer 30 is completed, control valve 28 is closed as controlled by pressure conditions and control valve 29 remains opened. Primary cylinder 31 is thus in communication with high-level tank 3. Fluid, for example, of 5 excess atmospheres, flows from liquid-air vessel 38 through line 37 and the open inlet valve 36 into secondary cylinder 32 to exert pressure on the piston 34, 33 which, in turn, expels fluid from primary cylinder 31 due to movement of primary piston portion 33. The fluid moves through lines 27, 2a into the high-level tank. The reciprocal movement of piston l3, 14 is repeated until piston portions 13 and 14 have reached their starting position for the next working stroke of the press.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In a method of producing a high hydraulic operating pressure for rapidly moving press plungers of forging presses of the type having a pressure transducer with a primary side, supplied with fluid under pressure during a working stroke of the press plunger, and a high pressure secondary side communicating with the press cylinder, the improvement comprising storing hydraulic fluid under high gas pressure in a storage tank; during an initial portion of the working stroke of the press plunger, supplying the press cylinder with hydraulic fluid from the storage tank to subject the press plunger to the pressure of the hydraulic fluid in the storage tank; and then supplying gas under pressure from the storage tank to the primary side of the pressure transducer to effect a rapid increase in the pressure in the press cylinder to effect a correspondingly rapid movement of the press plunger.

2. A method for producing a high hydraulic pressure, according to claim 1, wherein the primary side of the pressure transducer is held constantly under the high gas pressure of the storage tank during the operation of the transducer.

3. In a method of producing a high hydraulic operating pressure, the improvement claimed in claim 1, including storing hydraulic fluid under high gas pressure in a second storage tank; and, in advance of the working stroke of the press plunger, filling the press cylinder with hydraulic fluid from the second storage tank.

4. In a method of producing a high hydraulic operating pressure, the improvement claimed in claim 3, including providing a back pressure transducer with a primary side arranged for connection to the first storage tank and a secondary side arranged for connection to the secondary side of the first-mentioned pressure transducer and to the second storage tank; and, following the working stroke of the press plunger, supplying the primary side of the back pressure transducer with hydraulic fluid from the first storage tank to supply bydraulic fluid under pressure from the secondary side of the back pressure transducer to the secondary side of the first-mentioned transducer to restore the firstmentioned transducer to its starting position.

5. In apparatus for producing a high hydraulic operating pressure for rapidly moving press plungers of forging presses of the type having a pressure transducer with a primary side, supplied with fluid under pressure during a working stroke of the press plunger, and a high pressure secondary side communicating with the press cylinder, the improvement comprising, in combination, storage tank means storing hydraulic fluid under high gas pressure; first conduit means connecting the hydraulic fluid space of said storage tank means to said press cylinder to subject the press plunger to the pressure of the hydraulic fluid in the storage tank during a working stroke of said press plunger; and second conduit means connecting the gas space of said storage tank means to the primary side of said pressure transducer to effect a rapid increase in the pressure in said press cylinder to effect a correspondingly rapid movement of said press plunger during its working stroke.

6. In apparatus for producing a high hydraulic operating pressure, the improvement claimed in claim 5, in which said storagetank means comprises at least one pressure tank containing hydraulic fluid and gas under high pressure; and pump means operable to maintain the pressure in said pressure tank.

'7. In apparatus for producing a high hydraulic operating pressure, the improvement claimed in claim 5, including pump means connected to the hydraulic fluid space of said storage tank means and to the secondary side of said pressure transducer; said pump means being operable, upon completion of the working stroke of said press plunger, to supply hydraulic fluid under pressure to the secondary side of said pressure transducer to restore said pressure transducer to its starting position.

8. An apparatus for supplying a high pressure, according to claim 5, wherein the transmission ratio of gas pressure to liquid pressure in said pressure transducer varies between 1 to 2 and from 1 to 5.

9. In apparatus for producing a high hydraulic operating pressure, the improvement claimed in claim 8, in which said pump means comprises a back pressure transducer with a primary side and a secondary side; a second storage tank containing hydraulic fluid under gas pressure; means operable, during a working stroke of said back pressure transducer, to connect the primary side thereof to the hydraulic fluid space of said storage tank means and to connect the secondary side thereof to the secondary side of said first-mentioned pressure transducer; and means operable, during a return stroke of said back pressure transducer, to connect the secondary side thereof to the hydraulic fluid space of said second storage tank and to connect the primary side thereof to a hydraulic fluid return line. 

1. In a method of producing a high hydraulic operating pressure for rapidly moving press plungers of forging presses of the type having a pressure transducer with a primary side, supplied with fluid under pressure during a working stroke of the press plunger, and a high pressure secondary side communicating with the press cylinder, the improvement comprising storing hydraulic fluid under high gas pressure in a storage tank; during an initial portion of the working stroke of the press plunger, supplying the press cylinder with hydraulic fluid from the storage tank to subject the press plunger to the pressure of the hydraulic fluid in the storage tank; and then supplying gas under pressure from the storage tank to the primary side of the pressure transducer to effect a rapid increase in the pressure in the press cylinder to effect a correspondingly rapid movement of the press plunger.
 2. A method for producing a high hydraulic pressure, according to claim 1, wherein the primary side of the pressure transducer is held constantly under the high gas pressure of the storage tank during the operation of the transducer.
 3. In a method of producing a high hydraulic operating pressure, the improvement claimed in claim 1, including storing hydraulic fluid under high gas pressure in a second storage tank; and, in advance of the working stroke of the press plunger, filling the press cylinder with hydraulic fluid from the second storage tank.
 4. In a method of producing a high hydraulic operating pressure, the improvement claimed in claim 3, including providing a back pressure transducer with a primary side arranged for connection to the first storage tank and a secondary side arranged for connection to the secondary side of the first-mentioned pressure transducer and to the second storage tank; and, following the working stroke of the press plunger, supplying the primary side of the back pressure transducer with hydraulic fluid from the first storage tank to supply hydraulic fluid under pressure from the secondary side of the back pressure transducer to the secondary side of the first-mentioned transducer to restore the first-mentioned transducer to its starting position.
 5. In apparatus for producing a high hydraulic operating pressure for rapidly moving press plungers of forging presses of the type having a pressure transducer with a primary side, supplied with fluid under pressure during a working stroke of the press plunger, and a high pressure secondary side communicating with the press cylinder, the improvement comprising, in combination, storage tank means storing hydraulic fluid under high gas pressure; first conduit means connecting the hydraulic fluid space of said storage tank means to said press cylinder to subject the press plunger to the pressure of the hydraulic fluid in the storage tank during a working stroke of said press plunger; and second conduit means connecting the gas space of said storage tank means to the primary side of said pressure transducer to effect a rapid increase in the pressure in said press cylinder to effect a correspondingly rapid movement of said press plunger during its working stroke.
 6. In apparatus for producing a high hydraulic operating pressure, the improvement claimed in claim 5, in which said storage tank means comprises at least one pressure tank containing hydraulic fluid and gas under high pressure; and pump means operable to maintain the pressure in said pressure tank.
 7. In apparatus for producing a high hydraulic operating pressure, the improvement claimed in claim 5, including pump means connected to the hydraulic fluid space of said storage tank means and to the secondary side of said pressure transducer; said pump means being operable, upon completion of the working stroke of said press plunger, to supply hydraulic fluid under pressure to the secondary side of said pressure transducer to restore said pressure transducer to its starting position.
 8. An apparatus for supplying a high pressure, according to claim 5, wherein the transmission ratio of gas pressure to liquid pressure in said pressure transducer varies between 1 to 2 and from 1 to
 5. 9. In apparatus for producing a high hydraulic operating pressure, the improvement claimed in claim 8, in which said pump means comprises a back pressure transducer with a primary side and a secondary side; a second storage tank containing hydraulic fluid under gas pressure; means operable, during a working stroke of said back pressure transducer, to connect the primary side thereof to the hydraulic fluid space of said storage tank means and to connect the secondary side thereof to the secondary side of said first-mentioned pressure transducer; and means operable, during a return stroke of said back pressure transducer, to connect the secondary side thereof to the hydraulic fluid space of said second storage tank and to connect the primary side thereof to a hydraulic fluid return line. 